JP4353788B2 - Pneumatic tire - Google Patents

Description

    The present invention relates to a pneumatic tire in which a belt reinforcing layer in which reinforcing elements extending in the circumferential direction are embedded is disposed between a carcass layer and a belt layer.

In the past, the present applicant has proposed an invention that can effectively suppress the separation between the belt layer and the belt reinforcing layer in a pneumatic tire having an aspect ratio of 0.70 or less.
JP 2003-154808 A

  This is a carcass layer that extends in a toroidal shape between the pair of beads, and a reinforcing element that is disposed radially outside the carcass layer and is inclined at an inclination angle of 40 to 60 degrees with respect to the tire equator. A belt layer composed of at least one belt ply and a belt layer composed of at least one reinforcing ply disposed between the carcass layer and the belt layer and having a reinforcing element extending substantially in the circumferential direction embedded therein. Layer and a tread disposed radially outward of the belt layer, the width P of the widest reinforcing ply that is the widest width is 0.6 times or more the tire width W, and the widest belt ply that is the widest width It is wider than the widest reinforcing ply.

    As a result, it has become possible to suppress the interlayer separation to a considerable extent, but in recent years, the flattening of pneumatic tires has further progressed with the increase in the speed and the floor of the vehicle. There is an increasing need to more strongly suppress separation between belt-reinforced layers.

  An object of the present invention is to provide a pneumatic tire that can strongly suppress separation between a belt layer and a belt reinforcing layer.

    In response to such a need, the present inventor has conducted earnest research, and that bending deformation in the width direction that occurs in order to absorb the diameter difference in the tread portion at the time of ground contact is one of the causes of the interlayer separation. I found. In other words, the tread portion of the pneumatic tire has a diameter difference as the outer diameter decreases from the tread center toward the tread end. Such a diameter difference is caused by the tread portion (belt layer, belt reinforcing layer, etc.) ) Is absorbed by bending deformation in the width direction, and as a result, the tensile deformation in the circumferential direction that increases toward the outer end in the width direction occurs in the belt layer and the belt reinforcing layer.

  Here, since a reinforcing element extending substantially in the circumferential direction is embedded in the belt reinforcing layer, the belt reinforcing layer can hardly extend in the circumferential direction, but the belt layer is inclined with respect to the tire equator. Since the reinforcing element is embedded, the belt layer extends more in the circumferential direction than the belt reinforcing layer.

  In particular, when the widest belt ply, which is the widest width as described above, is wider than the widest reinforcing ply, the outer edge in the width direction of one widest belt ply exists outside the widest reinforcing ply in the width direction. As a result, the force for restraining the rubber between the cords is lost, and the circumferential extension of the widest belt ply in the width direction is considerably increased. For this reason, a large circumferential shear strain occurs between the belt layer and the widthwise outer end of the belt reinforcing layer.

  In order to suppress such shear strain in the circumferential direction, a wide belt ply wider than the widest reinforcing ply and narrower than the widest belt ply is arranged outside the widest belt ply in the radial direction as conventionally known. In addition, it is conceivable to embed a reinforcing element inclined in the opposite direction to the reinforcing element in the widest belt ply in the wide belt ply. In this case, as described below, the circumferential direction described above is used. Due to this tensile deformation, shear strain in a large cross section is generated between the belt layer and the outer end in the width direction of the belt reinforcing layer, resulting in interlayer separation.

  That is, both the belt layer and the belt reinforcing layer are reduced in width by the tensile deformation in the circumferential direction described above, but the reinforcing element embedded in the belt reinforcing layer extends substantially in the circumferential direction. The rigidity is equal to the rigidity of the rubber itself. As a result, the belt reinforcing layer is greatly reduced in the width direction. On the other hand, since the reinforcing elements embedded in the belt layers (the widest belt ply and the wide belt ply) cross each other across the tire equator, these reinforcing elements are stretched and the rigidity in the width direction is high. As a result, the amount of reduction in the width direction of the belt layer is considerably smaller than that of the belt reinforcing layer, and this causes a large cross-sectional shear strain between the belt layer and the outer edge of the belt reinforcing layer in the width direction. To do.

  Therefore, the present inventor has further researched, and if a narrow reinforcing layer that overlaps only in the vicinity of the width direction outer end of the belt reinforcing layer is disposed, the shear strain in the circumferential direction is reduced while reducing the shear strain in the cross section. It was found that it can be suppressed.

  The present invention has been made on the basis of the above-described knowledge. The carcass layer extends in a toroidal manner between the pair of beads, and is disposed on the radially outer side of the carcass layer, and is inclined at 40 to 70 degrees relative to the tire equator S. A belt layer composed of at least one belt ply in which a reinforcing element inclined at an angle A is embedded, and a reinforcing element which is disposed between the carcass layer and the belt layer and extends substantially in the circumferential direction is embedded. A belt reinforcing layer made of at least one reinforcing ply and a tread disposed radially outward of the belt layer, the width P of the widest reinforcing ply being the widest width being at least 0.6 times the tire width W In addition, in the pneumatic tire in which the widest belt ply which is the widest width is wider than the widest reinforced ply, the width of the widest reinforced ply is radially outward of the widest belt ply. The above-mentioned object is achieved by disposing a narrow reinforcing layer in which reinforcing elements inclined in the opposite direction to the reinforcing elements in the widest belt ply are embedded in the inner and outer ends, respectively. .

  In the present invention, a reinforcing element inclined in the direction opposite to the reinforcing element in the widest belt ply is embedded inside the widest belt ply so as to straddle the widthwise outer end of the widest reinforcing ply on the radially outer side of the widest belt ply. Since the narrow reinforcing layer is disposed, the rigidity in the circumferential direction is increased at the portion where the reinforcing layer and the widest belt ply overlap, and the circumferential extension at the outer end in the width direction of the widest belt ply is increased. Reduced. As a result, it is possible to effectively suppress the circumferential shear strain generated between the belt layer and the widthwise outer end of the belt reinforcing layer.

  In addition, since the above-described reinforcing layer is narrow, the reinforcing element embedded therein is interrupted on the way to the tire equator, and as a result, the tension of the intersecting reinforcing element becomes weak and the width direction of the belt layer The width-direction rigidity at the outer end portion is lowered, thereby effectively reducing the shear strain in the cross section generated between the belt layer and the width-direction outer end portion of the belt reinforcing layer. For this reason, the separation between the belt layer and the belt reinforcing layer is strongly suppressed.

Here, by extending the reinforcing layer inward in the width direction, when the distance from the widthwise outer end of the widest reinforcing ply to the widthwise inner end of the reinforcing layer exceeds 1/6 × width L, There is a possibility that separation will occur due to an increase in shear strain in the cross section. However, if configured as described in claim 2, the above-mentioned situation can be prevented.
Furthermore, if comprised as described in Claim 3, the circumferential rigidity in an overlap part can be effectively made high, suppressing the interlayer separation between the widest belt ply and a reinforcement layer.

According to the fourth aspect of the present invention, the interlayer rubber gauge between the widthwise outer ends of the widest reinforcing ply and the belt ply is thickened, thereby reducing both of the two shear strains described above. Can be made.
Furthermore, if constituted as in claim 5, the two shear strains can be effectively reduced while preventing manufacturing problems such as air entry.
According to the sixth aspect of the present invention, since the rubber layer absorbs the shear strain, the deformation of the coating rubber of the belt ply can be effectively reduced.

Furthermore, if comprised as described in Claim 7, the said shear strain can be reduced effectively, preventing destruction of the intermediate | middle rubber layer itself.
According to the eighth aspect of the present invention, it is possible to effectively reduce the shear strain while suppressing the occurrence of separation at both outer ends in the width direction of the widest belt ply.
Furthermore, if comprised as described in Claim 9, generation | occurrence | production of the separation in the width direction both outer side end of the widest width | variety reinforcement ply can be suppressed.
Further, according to the tenth aspect of the present invention, it is possible to effectively suppress both the separation on both lateral ends of the widest reinforcing ply in the width direction and the separation on both lateral ends of the widest belt ply. it can.

Further, according to the eleventh aspect of the present invention, the separation of the widest reinforcing ply in the width direction at both outer ends, the separation at the widthwise outer ends of the widest belt ply, and the interlayer separation between these two plies Can be suppressed.
Further, in a pneumatic tire having an aspect ratio of 0.70 or less, the bending deformation generated by the projection input is the largest in the carcass layer farthest from the bending center, and the carcass layer may be broken. However, if configured as described in claim 12, bending deformation of the carcass layer can be effectively suppressed.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
In FIGS. 1 and 2, reference numeral 11 denotes a heavy-duty pneumatic radial tire having a flatness ratio of 0.70 or less that is mounted on a truck or bus. The pneumatic tire 11 has a pair of bead portions 12. A pair of beads 13 (which are a pair here, but may be a plurality of pairs) are embedded. The pneumatic tire 11 includes a sidewall portion 14 extending from the bead portion 12 toward the outer side in the substantially radial direction, and a substantially cylindrical tread portion 15 that connects the radially outer ends of the sidewall portions 14 to each other. And further.

  The pneumatic tire 11 has a carcass layer 18 that extends between the beads 13 in a toroidal manner and reinforces the sidewall portions 14 and the tread portions 15, and both ends of the carcass layer 18 extend around the beads 13. It is folded from the inside to the outside. The carcass layer 18 is composed of at least one, in this case, one carcass ply 19, and inside the carcass ply 19 is a non-stretchable reinforcing element 20, such as a steel cord, extending substantially in the radial direction (meridian direction). There are many buried. Further, a chafer 21 reinforced with, for example, a steel cord is disposed around the carcass layer 18 in the bead portion 12.

  In FIGS. 1, 2, and 3, reference numeral 24 denotes a belt layer disposed on the outer side in the radial direction of the carcass layer 18, and this belt layer 24 extends from the tire equator S toward the outer sides in the width direction by at least one piece. The belt ply 25 is composed of a single belt ply 25, and a plurality of non-stretchable reinforcing elements 26 made of, for example, steel or aramid fibers are embedded in the belt ply 25. Here, since the belt layer 24 is composed of one belt ply 25 as described above, the belt ply 25 is the widest belt ply. When the belt layer 24 is formed by laminating two or more belt plies 25, the inclination directions of the reinforcing elements in the belt plies 25 may be the same direction, or the opposite directions may be crossed. Also good. However, when used in an intersecting manner, the width of one sheet must be narrower than the belt reinforcing layer described later (if both sheets are wider than the belt reinforcing layer, the distortion between the belt reinforcing layer and the belt ply as described above). Because it gets worse).

  Further, the reinforcing element 26 embedded in the belt ply 25 has a circumferential shear strain based on a difference in a circumferential deformation amount between the belt ply 25 and an outer end portion in the width direction of a belt reinforcing layer described later. In order to reduce this, the tire equator S is inclined at an inclination angle A of 40 degrees or more. However, if the inclination angle A exceeds 70 degrees, it is impossible to ensure the shearing rigidity (ensurement of performance such as wear), which is the original purpose of the belt layer 24. Therefore, the inclination angle A must be 70 degrees or less. . Reference numeral 28 denotes a top tread disposed on the radially outer side of the carcass layer 18 and the belt layer 24, and reference numeral 29 denotes a side tread disposed on both outer sides in the axial direction of the carcass layer 18.

  31 is a belt reinforcing layer disposed radially inward of the belt layer 24, more specifically, between the carcass layer 18 and the belt layer 24 so as to overlap the belt layer 24. At least one belt reinforcing layer 31 is provided. Here, it is composed of two reinforced plies 32 laminated. Each reinforcing ply 32 has a reinforcing element 33 that extends substantially in the circumferential direction and is made of steel, aramid fiber, or the like. The reinforcing element 33 is made of a cord (stranded wire) or a monofilament, Many lines appear on the meridional section of reinforced ply 32. In this embodiment, the reinforcing element 33 is bent in a wave shape (zigzag shape), but may be extended linearly in the circumferential direction. Here, when the reinforcing element 33 extending linearly is used, it is preferable to use a cord having an initial elongation in order to ensure expansion during manufacturing.

  Here, each reinforcing ply 32 is configured by, for example, winding a small number of reinforcing elements 33 and arranging a ribbon-like body covered with rubber around the outer side of the carcass layer 18 in a spiral manner. Further, among the reinforced plies 32, the widest reinforced ply which is the widest width (here, both the inner and outer reinforced plies 32a and b are equal in width, so both the reinforced plies 32a and b become the widest reinforced ply. ) Is narrower than the width L of the belt ply 25, which is the widest width, and conversely, the width L is wider than the width P. The outer end 35 is located on the outer side in the width direction from the outer ends 36 in the width direction of the widest width reinforcing plies 32a, b.

  The width P of the widest reinforcing ply 32a, b is 0.6 times or more the tire width W, here 0.69 times. Here, the reason why the width P of the reinforced plies 32a and 32b, which is the widest width, is 0.6 times or more of the tire width W is that, as described above, in the pneumatic tire 11 having a flatness ratio of 0.70 or less, the diameter growth due to internal pressure filling is increased. It is for suppressing effectively.

  However, in the case of the pneumatic tire 11 having such a structure, the bending deformation in the width direction that occurs to absorb the diameter difference in the tread portion 15 at the time of ground contact as described above is caused by the belt layer 24 and the belt reinforcing layer 31. A large circumferential shear strain is generated between the outer end portions in the width direction, and separation between these layers is finally generated. On the other hand, in order to solve such problems, when a wide belt ply is arranged outside the widest belt ply 25, the rigidity in the width direction differs greatly between the belt layer and the belt reinforcing layer, so the belt layer and the belt reinforcing A large shear strain in the cross section is generated between the outer end of the layers in the width direction, and this also causes interlayer separation.

  For this reason, in this embodiment, a state in which a pair of reinforcement layers 38 straddling the widthwise outer ends 36 of the narrowest and widest reinforcing plies 32a and b are respectively in close contact with the radially outer side of the widest belt ply 25. And a plurality of reinforcing elements 39 inclined in the opposite direction to the reinforcing elements 26 in the widest belt ply 25 are embedded in the reinforcing layers 38.

  As a result, the circumferential rigidity is increased at the portion where the reinforcing layer 38 and the widest belt ply 25 are overlapped, and the circumferential elongation at the outer end in the width direction of the widest belt ply 25 is reduced. As a result, the circumferential shear strain generated between the belt layer 24 and the outer end in the width direction of the belt reinforcing layer 31 is effectively suppressed.

  Further, since the reinforcing layer 38 is narrow, the reinforcing element 39 embedded therein is interrupted on the way to the tire equator S, and as a result, the tension of the intersecting reinforcing elements 26 and 39 is weakened. Thus, the width direction rigidity at the outer end portion in the width direction of the belt layer 24 is lowered, thereby effectively reducing the shear strain in the cross section generated between the belt layer 24 and the outer end portion in the width direction of the belt reinforcing layer 31. Is done. For this reason, the separation between the belt layer 24 and the belt reinforcing layer 31 is strongly suppressed.

  Here, the width Q of the reinforcing layer 38 is preferably 0.05 times or more the width L of the belt ply 25 which is the widest width. The reason is that if the width Q is less than 0.05 times the width L, the above-described shear strain may not be sufficiently reduced depending on the type of the pneumatic tire 11.

  The distance M from the widthwise outer end 36 of the widest reinforcing ply 32a, b to the widthwise inner end 40 of the reinforcing layer 38 is 1/6 times the width L or less (1/6 × width L), That is, the value of M / L is preferably 1/6 or less. The reason is that if the distance M exceeds 1/6 × width L by extending the reinforcing layer 38 inward in the width direction, the shear strain in the cross section increases and separation may occur. This is because such a situation can be prevented if the distance M is 1/6 × width L or less.

  On the other hand, the distance N from the widthwise outer end 36 of the widest reinforcing ply 32a, b to the widthwise outer end 41 of the reinforcing layer 38 is from the widthwise outer end 36 of the widest reinforcing ply 32a, b. It is preferable that the distance R to the outer end 35 in the width direction of the belt ply 25 is 0.8 times or less. The reason is that when the distance N exceeds 0.8 times the distance R, a large in-section shear strain is generated between the belt layer 24 and the belt reinforcing layer 31 due to circumferential elongation at the time of ground contact.

  Further, the reinforcing element 39 in the reinforcing layer 38 is made of, for example, non-stretchable steel or aramid fiber, like the reinforcing element 26 in the belt ply 25. The inclination angle B of the reinforcing elements 39 with respect to the tire equator S is preferably in the range of 15 to 70 degrees. The reason is that if the inclination angle B is less than 15 degrees, interlayer separation may occur between the widest belt ply 25 and the reinforcing layer 38, whereas if the inclination angle B exceeds 70 degrees. This is because the circumferential rigidity at the overlapping portion of the widest belt ply 25 and the reinforcing layer 38 cannot be sufficiently increased, but if it is within the above range, while suppressing the above-described interlayer separation, The circumferential rigidity in the overlapping portion can be effectively increased.

  Further, as described above, when the outermost ends 35 in the width direction of the belt ply 25 having the widest width are positioned more outward in the width direction than the outer ends 36 in the width direction of the widest reinforcing plies 32a and 32b, 32a, b, where the rubber layer 45 is interposed while the rubber gauge is E (mm) between the outer ends of the outer reinforcing ply 32b in the width direction and the belt ply 25 at the portion disposed in close contact therewith. It is preferable to do. The reason is that when the intermediate rubber layer 45 is interposed at such a position, the above-mentioned outer ends of the reinforcing plies 32a and 32b that generate shear strain and the belt ply 25 adjacent to each other are formed between the layers. This is because the rubber gauge becomes thick, so that two shear strains between them can be reduced together.

  When the intermediate rubber layer 45 is interposed as described above, the reinforcing element 33 and the reinforcing element are described in detail between the widthwise outer ends of the widest reinforcing ply 32b and the belt ply 25 in the overlapping portion. The value of the rubber gauge G between 26 and 26 becomes large. The value of this rubber gauge G is tb and tk for the coating rubbers 47 and 48 of the belt ply 25 and the reinforcing ply 32, respectively. When the value of T is T, the total gauge T is preferably in the range of 2 to 10 times.

  The reason is that if the rubber gauge G is less than twice the total gauge T, the shear strain between the outer ends of the widest reinforcing plies 32a and 32b and the belt ply 25 is effectively reduced. On the other hand, if it exceeds 10 times, the effect of reducing the shear strain is saturated, and manufacturing problems such as air entry occur.

  Here, the coating rubber 47 of the belt ply 25 described above usually has a JIS hardness higher than that of the coating rubber 48 of the reinforcing ply 32, but the JIS hardness of the rubber constituting the rubber layer 45 is higher. It is preferable that the coating rubber 47 of a certain belt ply 25 has a JIS hardness or less. The reason is that the rubber layer 45 is present between the outer ends of the widthwise direction of the reinforcing plies 32a and 32b, which are the widest width, and the belt ply 25, so that the shear strain can be absorbed. It is because it can reduce effectively.

  Further, the lower the JIS hardness of the rubber constituting the intermediate rubber layer 45, the stronger the shear strain is absorbed and the strain concentration in the coating rubbers 47 and 48 can be prevented. Is preferably 80 degrees or less. However, if the JIS hardness of the rubber constituting the intermediate rubber layer 45 is less than 55 degrees, the intermediate rubber layer 45 itself may be destroyed by deformation during load rolling. It is preferable to do.

  Further, it is preferable that the outer end 49 in the width direction of the rubber layer 45 is located on the inner side in the width direction from the outer ends 35 in the width direction of the belt ply 25 having the widest width. The reason is that in the ground contact area, the top tread 28 is compressed and deforms so as to bulge outward in the width direction, but the rubber layer 45 of the belt ply 25 has a relatively low hardness as described above. If the belt extends beyond the outer ends 35 in the width direction to the outer side in the width direction, the rigidity of the top tread 28 is reduced by the influence of the intermediate rubber layer 45, and the deformation is promoted. As a result, the belt having the widest width This is because separation may occur at both outer ends 35 in the width direction of the ply 25.

  Further, in this embodiment, in addition to the above-described rubber layer 45, the JIS hardness of the coating rubber 48 of the reinforced ply 32 having a JIS hardness on both outer sides (left and right sides) in the width direction of the widest reinforcing plies 32a and 32b. The transverse rubber layers 52 made of the rubber as described above are disposed. If the lateral rubber layer 52 having a hardness higher than that of the coating rubber 48 of the reinforcing ply 32 is arranged on both outer sides in the width direction of the reinforcing ply 32 (left and right side) in this way, the distortion in the lateral direction of the outer end 36 in the width direction of the reinforcing ply 32 is obtained. And the occurrence of separation at the site can be suppressed.

  If the widthwise outer end 53 of the lateral rubber layer 52 is extended from the widthwise outer end 35 of the widest belt ply 25 to the widthwise outer side, the width of the widest belt ply 25 is increased. It is also possible to suppress distortion at the outer end 35 in the direction, thereby suppressing the occurrence of separation at the outer end 35 in the width direction of the widest belt ply 25 as well as the outer end 36 in the width direction of the reinforcing ply 32. be able to.

  Here, the JIS hardness of the rubber constituting the transverse rubber layer 52 is preferably higher than the JIS hardness of the rubber constituting the intermediate rubber layer 45. In this way, the reinforcement plies 32a and b having the widest width are provided. Separation at the side of the widthwise outer ends 36, separation at the widthwise outer ends 35 of the widest belt ply 25, and interlayer separation between the plies 25 and 32 can be strongly suppressed.

    FIG. 4 shows a second embodiment of the present invention. In this embodiment, a carcass protective layer 56 is disposed between the belt reinforcing layer 31, specifically, the inner reinforcing ply 32 a and the carcass layer 18. Here, a plurality of reinforcing elements 57 inclined at an angle of substantially 90 degrees, which is the same as the reinforcing element 20 of the carcass layer 18, here are 70 degrees or more with respect to the tire equator S inside the carcass protective layer 56. Buried.

  The reason why such a carcass protective layer 56 is provided between the reinforced ply 32 and the carcass layer 18 is that bending deformation caused by projection input occurs when the flat ratio of the pneumatic tire 11 is 0.70 or less as described above. Is the largest in the carcass layer 18 that is farthest from the bending center, and the carcass layer 18 may break. However, the carcass protective layer 56 effectively prevents such bending deformation of the carcass layer 18. This is because it can be suppressed. Other configurations and operations are the same as those in the first embodiment.

    Next, test examples will be described. In this test, the conventional tire 1 from which the reinforcing layer and the intermediate rubber layer are removed from the pneumatic tire of the first embodiment, the conventional tire 2 from which the reinforcing layer is removed from the pneumatic tire of the first embodiment, The conventional tire 3 in which the reinforcing layer is removed from the pneumatic tire of the first embodiment and the belt layer is composed of two belt plies, the test tires 1 to 12 having the same configuration as the first embodiment, the first A test tire 13 having the same configuration as that of the second embodiment was prepared.

  Each of the tires described above has a tire size of 435 / 45R22.5, a tire width W of 435 mm, a width L of the widest belt ply of 360 mm, and an inclination angle A of the reinforcing element in the widest belt ply. Ascending to the right, the widest reinforced ply width P is 300mm, the reinforced ply coating rubber gauge tk is 0.35mm, the belt ply coating rubber gauge tb is 0.30mm, and the total gauge T of these two coating rubbers is 0.65mm. The JIS hardness of the reinforced ply coating rubber is 70 degrees, the JIS hardness of the belt ply coating rubber is 76 degrees, the JIS hardness of the intermediate rubber layer is 70 degrees, and the width of the intermediate rubber layer is 30 mm (only the test tire 12 is 50 mm). The JIS hardness of the horizontal rubber layer was 76 degrees.

  In the conventional tire 3, a wide belt ply is arranged on the radially outer side of the widest belt ply. The width of the wide belt ply is 340 mm, and the inclination angle of the internal reinforcing element is 52 degrees ascending to the left. The width of the carcass protective layer in the test tire 13 was 200 mm, and the inclination angle of the internal reinforcing element with respect to the tire equator S was 90 degrees. Further, the width Q (mm) of the reinforcing layer in each tire, the slope angle B (degrees) of the reinforcing element in the reinforcing layer that is raised to the left with respect to the tire equator S, a value M / L obtained by dividing the distance M by the width L, rubber gauge The value G / T obtained by dividing G by the total gauge T is shown in Table 1 below.

  Next, each of these tires was mounted on a rim having a size of 14.00 × 22.5, filled with an internal pressure of 900 kPa, and then run on a drum at 60 km / h until separation occurred while applying a load of 59.0 kN. The results are shown in the index of driving index in Table 1 with the conventional tire 1 being 100. Here, the index 100 was 27,500 km. Further, the occurrence of separation is the outer end in the width direction of the belt reinforcing layer in the conventional tires 1 to 3, the test tires 1 to 5 and 8 to 13, and the belt ply and the reinforcing layer in the test tires 6 and 7. It was between.

  The present invention can be applied to the industrial field of pneumatic tires.

It is a meridian half section view of a pneumatic tire showing a first embodiment of the present invention. It is a partially broken top view of a tread part. It is an expanded meridian sectional drawing of the vicinity of a rubber layer. It is a partially broken top view similar to FIG. 2 which shows 2nd Embodiment of this invention.

Explanation of symbols

11 ... Pneumatic tire 13 ... Bead
18 ... Carcass layer 24 ... Belt layer
25 ... Belt ply 26 ... Reinforcing element
28 ... Tread 31 ... Belt reinforcement layer
32… Reinforced ply 33… Reinforcing element
38 ... Reinforcing layer 39 ... Reinforcing element
45… Rubber layer 47… Coating rubber
48 ... Coating rubber 52 ... Horizontal rubber layer
56… Carcass protective layer 57… Reinforcing element

Claims (12)

    A carcass layer extending in a toroidal shape between a pair of beads, and a reinforcing element that is disposed radially outside the carcass layer and that is inclined at an inclination angle A of 40 to 70 degrees with respect to the tire equator S is embedded. A belt layer made of one belt ply, and a belt reinforcing layer made of at least one reinforcing ply disposed between the carcass layer and the belt layer and having a reinforcing element extending substantially in the circumferential direction embedded therein. And a tread disposed radially outward of the belt layer, and the width P of the widest reinforcing ply that is the widest width is not less than 0.6 times the tire width W, and the widest belt ply that is the widest width is In the pneumatic tire wider than the wide reinforcing ply, the outer wide end of the widest reinforcing ply is straddled on the radially outer side of the widest belt ply, and the widest belt is inside. A pneumatic tire, wherein a reinforcing element is inclined reinforcing element opposite direction in Lai placed the narrow reinforcing layer is embedded.     2. The air according to claim 1, wherein when the width of the widest belt ply is L, the distance M from the widthwise outer end of the widest reinforcing ply to the widthwise inner end of the reinforcing layer is 1/6 × width L or less. Enter tire.     The pneumatic tire according to claim 1 or 2, wherein an inclination angle B of the reinforcing element embedded in the reinforcing layer with respect to the tire equator S is in a range of 15 degrees to 70 degrees.     The pneumatic tire according to any one of claims 1 to 3, wherein a rubber layer is interposed between both end portions in the width direction of the widest reinforcing ply and a belt ply at a portion overlapping with the end portion.     When the total of the coating rubber gauges of the reinforced ply and the belt ply is T, the outer side end portions in the width direction of the widest reinforced ply and the belt ply in a portion overlapping with the widest reinforced ply by the interposition of the rubber layer between The pneumatic tire according to claim 4, wherein the rubber gauge G is between 2 to 10 times the total gauge T.     The pneumatic tire according to claim 4 or 5, wherein the intermediate rubber layer is made of rubber having a JIS hardness equal to or less than the JIS hardness of the belt-ply coating rubber.     The pneumatic tire according to claim 6, wherein the intermediate rubber layer is made of rubber having a JIS hardness in a range of 55 to 80 degrees.     The pneumatic tire according to any one of claims 4 to 7, wherein an outer end in the width direction of the intermediate rubber layer is positioned inward in the width direction from both outer ends in the width direction of the widest belt ply.     The pneumatic according to any one of claims 1 to 8, wherein a transverse rubber layer made of rubber having a JIS hardness equal to or higher than a JIS hardness of a coating rubber of the reinforced ply is arranged on both outer sides in the width direction of the widest reinforced ply. tire.     The pneumatic tire according to claim 9, wherein an outer end in the width direction of the lateral rubber layer extends from an outer end in the width direction of the widest belt ply to an outer side in the width direction.     The pneumatic tire according to claim 9 or 10, wherein the lateral rubber layer is made of rubber having a JIS hardness higher than that of the intermediate rubber layer.     The carcass protective layer in which a reinforcing element inclined at an angle of 70 degrees or more with respect to the tire equator S is embedded inside the belt reinforcing layer and the carcass layer. The described pneumatic tire.

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